R129 500SL '93 - Replacement Cat?
 

Unfortunately that time has come when my original cat has started to show the signs of failure and so I wanted to canvas others opinions on OEM replacements and patent Cats.

MB have quoted 1400UKP which is ok should you wish to keep the car for another 15 years and is probably reasonable value, however I can't plan that far in advance so I'm looking for a quality replacement at an economic price.

It's firstly a single box three way unit (thankfully) and the gas analysis shows a perfect lambda (1.000, fluctuating +/- 0.002) so I assume that the lambda sensor and control system is fine. However CO is around 0.2 to 0.5 fluctuating (even after giving the car a pounding) and here in the UK the limit has just been reduced from 0.3 to 0.2!

Has anyone experience of OEM (who is the OEM?) or patent (third party manufacturer's) replacements?

Although this is a cross post from the SL forum I feel it's slightly justified as Cats are really quite general.


Any thoughts chaps?
Lea

Blimey - someone must have bought an aftermarket cat for their benz by now?!

Forget the car model, surely someone can comment on third party cats in general? - please....

Cheers
Lea

What do you mean by failure?, are you being forced to do something about your emissions?, are you sure that your emission output isn't due to a problem with fuel system?. :)

Every year here in the UK cars are subject to a check called the MOT and unfortunately one test is Co emissions. So, yep I'm being forced!

Cats over their life typically exhibit a CO output of around 10 times less than mine, however just before complete failure they reach CO levels similar which can be clearly seen using gas analysis.

The car's fuel mixture is spot-on at a lambda of 1.000 +/-0.005 and so the LH unit and O2 sensor is operating fine.

Of course a possible way around the emissions test would be to flood the exhaust with air by putting a 'quiet' hole in it, but in the UK the air/fuel ratio is also checked for exactly this!